Fotonica in SURFnet6 Wouter Huisman Netwerkdiensten, SURFnet

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Fotonica in SURFnet6Wouter HuismanNetwerkdienste
n, SURFnet
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Agenda

• Fibers Infra
• Module Blocks
• Transmitter, Receivers, Amplifiers, Filters
• Systems
• Single channel lasers/receivers
• Amplified single channel
• C/DWDM
• DCM, PMD, FEC
• Latest technology
• SURFnets network

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Optical fiber - Historical perspective

• Internal reflection known from 19th century (John
  Tyndall, 1870)
• Early fibers with cladding extremely lossy
  1000dB/km (1960)
• Today fiber loss 0.2dB/km

Refractive index N1(water) gt N2 (air)
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Fiber basics

• Multi Mode (MM)
• Intra office
• SX
• max 500m
• Single Mode (SM)
• LX, ZX, C/DWDM

50 - 62µm
Core Cladding
5-10µm
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Fiber Loss (SM)
1310nm
1470nm-1620nm

• Fiber loss is wavelength dependent, minimum is
  around 1550nm

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Fiber plant layout
POP
Equipment
MMR
4km
4km
Splice
Handhole
Patching at ODF
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Fiber Plant test

• Basic paramaters
• - Length
• - Loss
• - Reflection

OTDR (optical time domain reflectometer)
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10Gb/s optical transmitter technologies

• External Modulation - DM-DFB (Directly Modulated
  Distributed Feed Back laser)
• Cheap, small, low power consumption
• Chirped, i.e. different wavelength during ones
  and zeros which leads to a wide optical
  spectrum and associated transmission impairments
• Used for short reach transmission

0,1,1,0,1,1,,0,1,0
DFB

• External Modulation - CW-DFB (Continuous Wave DFB
  laser) and MZ (Mach-Zehnder) combination
• Expensive, relatively large, high-power drivers
  (high power consumption)
• Excellent performance
• Typically used for DWDM (Dense Wavelength
  Division Multiplexing)

0,1,1,0,1,1,,0,1,0
DFB
Mach-Zehnder LiNbO3 modulator
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Typical optical receiver setup
data
BER
10-6
10-9
10-12
Prec (dBm)
Psens
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Traditional optical fiber transmission systems
Transmission fiber a (dB/km)
Tx
Rx
PT (dBm)
PR (dBm)
Transmission distance (PT-PR) / a (km)

• Combination of transmitter and receiver connected
  directly to dark fiber
• Typical distance is max 100km
• 150Mb/s -2.5Gb/s

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3R regeneration - OEO

• Transmitter Receiver 3R
• Re-amplification
• Re-timing
• Re-shaping

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EDFAs (Erbium Doped Fiber Amplifiers)

• Fiber doped with Er3 ions be excited by 980nm
  or 1480nm photons
• Spontaneous emission generates noise
• Excited state Erbium ions can be stimulated to
  decay to ground state via stimulated emission by
  a 1550nm signal

Pump laser
Outgoing
Incoming
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Single Channel System with amplifiers
Tx
Rx
OA
OA

• Pre and Post Amplifiers allow for longer single
  span Systems upto 240km
• 150Mb/s -2.5Gb/s

OLA
Tx
OA
Rx
OA
OLA
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Wavelength Division Multiplexing (C/DWDM)

• WDM filters, passive device
• Muxing coloured wavelength
• Spacing between ?s determines the number of
  channel per fiber
• SURFnets DWDM supports 72 ?s _at_ 10Gb/s

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DWDM System
OADM Node
Terminal Node
AMP Node
Terminal Node
OEO
OEO

DCF
DCF
DCF
Mux

Demux
DCF
DCF
OEO
OEO
OEO
OEO

Mux

Demux
DCF
DCF
DCF
DCF
DCF
OEO
OEO
OEO

• Typically 80 channels spaced at 100GHz using C
  and L band
• Each channel operating at 10Gb/s, thus 800Gb/s
  per fiber
• Limited Optical Add and Drop for point-to-point
  optical lightpaths

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Chromatic Dispersion

• Typical value dispersion (D) 17ps/nmkm

10Gb/s
?F
?T bitperiod
L Tb/ ? FD
Transmission Rate Spectral Width (?F) Bitperiod(Tb) Max distance (km)
2.5Gb/s 0.025 4x10-10 800
10Gb/s 0.1 1x10-10 50
40Gb/s 0.4 2.5x10-11 3
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Chromatic Dispersion
120km standard SMF D17.8 ps/nm km
Tx
Rx
OA
OA
rb 10Gb/s ?c 1557nm
120km-10Gb/s system configuration
011101101001001
011101101001001
Optical pulse shape at transmitter output
After 120km transmission
Speed of Light is Wavelength dependent
Chromatic dispersion affects pulse shape
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eDCM
Total 5000km standard transmission fiber H(f)
0,1,1,0,1,1,,0,1,0
Rx
DFBMZ
?
OA
OA
OA
h-1 (t)
D87500ps/nm
dispersion compensation off
z5000km
z0km
D-87500ps/nm
dispersion compensation on
z5000km
z0km
No more need for dispersion compensation via DCFs
(Dispersion Compensating Fibers)!!
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PMD
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FEC

• Forward Error Correction
• Technique to improve bit error rate resulting
  better Preceiver
• Adding FEC increases bitrate ? worse Preceiver

BER
FEC on
10-6
10-9
10-12
Prec (dBm)
Parity check indicates the single error bit
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New developments

• 40Gb/s and 100Gb/s
• QPSK/QAM 40G over 10Gb/s
• From Static to Dynamic
• MEMS Switchable mirrors
• Dynamic WDM
• eDCM
• Tunable lasers
• Tunable filters
• DRAC

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Layer 0 Evolution
OADM Node
Terminal Node
AMP Node
Terminal Node
OEO
OEO
DCF

DCF
DCF
Mux

Demux
DCF
DCF
OEO
OEO
OEO
OEO

Raman
Raman
Raman
Mux

Demux
DCF
DCF
DCF
DCF
DCF
OEO
OEO
OEO
Advanced FEC Advanced Signal Processing Higher
Spectral Efficiency (QPSK/QAM)
Remove Raman, Increase Performance Remove
DCMs Amps, Increase PMD Tolerance, Eliminate
complex engineering rules (esp. OADM) 4x
Capacity per Line and 40G Service Support
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Dynamic Networking
ROADM
ROADM
ROADM
ROADM
ROADM
ROADM
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SURFnet6

• third generation DWDM
• 10Gb/s per channel
• 50GHz channel spacing
• wavelength locking
• optical add/drop
• forward error correction
• dispersion compensation
• C-band, can be upgraded to add L-band

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Thanks!wouter.huisman_at_surfnet.nl